Automatic draft control for grain driers



Nov. 22, 1949 A. B. WELTY 2,433,753

AUTOMATIC DRAFT CONTROL FOR GRAIN DRIERS Filed Dec. 22, '1945 2 Sheets-Sheet l Nov. 22, 1949 A. B. WELTY AUTOMATIC DRAF'i CONTROL FOR GRAIN DRIERS 2 Sheets-Sheet 2 Filed Dec. 22, 1945 fiveizz of dz; PM

w g aw Patented Nov. 22, 1949 AUTOMATIC DRAFT CONTROL FOR GRAIN DRIERS Albert B. Welty, Moline, Ill., assignor to International Harvester Company, a corporation of New Jersey Application December 22, 1945, Serial No. 636,885

11 Claims.

This invention relates to a new and improved automatic draft control for grain dryers and has for one of its principal objects the provision of means for regulating the draft for furnaces used in conjunction with grain dryers.

An important object of this invention is to provide a valve positioned between a furnace and a source of suction and operable responsive 'to the amount of draft within the furnace.

Another important object of the present invention is to provide an automatic valve operating means to control furnacedraft in the grain dryer set forth in my copending application entitled Suction type grain dryer which has now issued as Patent No. 2,437,899.

As described in my copending application mentioned above, I employ an oil burning furnace for the source of heat necessary to dry the grain. It is common knowledge that furnaces require a draft in order that combustion take place. Usually a furnace is supplied with a stack or chimney which naturally creates sufficient draft to support combustion. However, in conjunction with my grain dryer it is practically impossible to employ a stack comparable to those used in homes or buildings, and hence it is necessary to artificially create the draft ordinarily created by a tall chimney. In my grain dryer I employ a suction fan to draw heated air up through a column of grain in order to cause drying of the grain. As shown in my earlier filed case on the entire grain dryer, I employ this same suction fan to create draft for my oil burning furnace. A manually operable valve is shown and hasbeen described in my prior case for regulating the amount of suction to be applied to the furnace flue. It is therefore an object of the present case to provide an automatically operable valve for regulating the amount of draft to he applied to the furnace and directly responsive to -the condition within the furnace.

Other and further important objects may become apparent from the followigg specification and accompanying drawings, in which:

Figure 1 is a vertical sectional view of my grain dryer showing the automatically operable draft valve incorporated therein and taken on the line I of Figure 3;

Figure 2 is an enlarged view of the automatically operable draft valve as shown in Fi ure 1.; and

33 of Figure 2.

As shown in the drawings:

Figure 3 is a sectional view taken on the line grain dryer or dehydrating chamber, The chamher I!) is enclosed within insulated Walls I I and Reference numeral 10 indicates generally a I2 and in the bottom thereof is equipped with plenum chambers l3, l4, and IS. The plenum chambers communicate directly with a source of heat created in this particular instance by an oil burning furnace. Screened apertures are provided at l6 and l1, l8 and I3, and 20 and 2| in the plenum chambers I3, l4 and I5 respectively. The chamber I0 is adapted to be filled with grain to be dried. The intake for the grain is at the top of the chamber through a conduit 22 which has spaced apertures in the bottom along the entire length thereof. An auger conveyor 23 is adapted to be rotated within the conduit 22 and feeds the grain to be dried therealong. When the grain dryer is in full operation the chamber I0 is entirely filled with grain, forming a substantial column of grain to be dried, The grain is discharged from the chamber of rolls 24, 25, 26, and 21 extending longitudinally of the chamber i0 and between of the plenum chambers l3, l4, and 15. Each of the discharge rolls 24, 25, 26, and 21 have pockets in'the periphery thereof at 28, 29, 30', and 3|, respectively, for reception of a predetermined quantity of dried grain. Upon rotation of the rolls the grain is dropped out of the pockets on the underside and into a compartm nt 32 be neath the plenum chambers and rolls. An auger conveyor 33 is positioned lengthwise of the com;

partment 32 and carries the dehydrated grainv to one end of the grain chamber 10 from which point it is elevated or otherwise carriedto storage bins.

As best shown in Figure 2, the flue gases .are drawn upwardly through a furnace radiator. The purpose of "the furnace radiator is to pass hot flue gases through a, plurality of conduits within and adjacent the grain in the heating chamber so that the major portion of the heat within the gases being discharged are transferred to the grain to be dried, thus effecting efficient furnace operation. A tubular conduit 35 extends the length of the grain chamber I0 and is shown in my copending application mentioned above. The conduit 35 discharges its flue gases into the outer hexagonal chamber 36. This hexagonal chamber 36 is adapted to carry the flue gases back through the length of the grain chamber-l0 and discharges the exhaust conduit 31. A butterfly valve .38 is pivoted'for rotational movement on a shaft 39 'journaled within the conduit 31,

A suction fan is provided at one end of the II] by a plurality.

and at t e s des al -e5 through the as best shown iniFigure 2.

grain chamber l8 and is positioned within the circular housing 40 as best shown in Figures 1 and 3. The primary function of the suction fan is to draw hot air created by a furnace (not shown) upwardly through the plenum chambers l3, l4, and through the column of downwardly discharging grain and out up over the top of the column of grain to the fan housing where it is exhausted through the large conduit 4|. The path of hot air travel is indicated by arrows 58 in Figure 3.

A second function of the suction fan is to provide draft for the furnace which supplies the heat for this grain dryer. If the flue gases were merely to exhaust to atmosphere through conduit 31, there would not be sufficient draft to maintain combustion in the furnace. Hence communication is provided between the furnace and the suction fan to draw the flue gases up through the furnace radiator and where they are exhausted through the conduit 31,

as indicated by the arrows 5|, joining with the suction fan stream of air indicated by the arrows 58. The amount of suction created by the fan is not always constant and hence the butterfly valve 38 must be opened or closed, more or less depending on the amount of suction and also depending on the amount of draft necessary to cause the furnace to burn efficiently.

The butterfl valve shaft 39 extends downwardly through the conduit 31 and has fixedly mounted on the end thereof an arm 42. The Outer end of the arm 42 is joined by a link 43 to an upwardly extending arm d4 of a bell-crank lever 45. The bell-crank lever 45 is pivoted at 46 on a bracket 52 fixedly attached to a partition wall 53. A downwardly extending armfi'l of the bell-crank 45 is adapted to swing within predetermined limits fixed by adjustable set screws 48 and 49. These set screws 48 and 49 threadedly engage cars 54 and 55, respectively, bent outwardly from the bracket 52. A rod-like link is pivotally attached to the lower end of the arm 41 and is attached at its other end at 51 to a lever arm 58. The lever 58 is pivoted at 58 on a fixed bracket 68 rigidly attached to the wall ll. diaphragm or bellows 8| is positioned within a compartment 51* on the side of the grain chamber and has a rearwardly extending post 62 piv-.

otally attached to the lever arm 58 at 83 spaced upwardly from the pivotal attachment 59 of the lever arm 58.

A small tube 64 joins the furnace radiator at 85 and the compartment 6| on one side of the diaphragm or bellows at 86. The diaphragm BI is provided with a chamber in the front thereof so that draft or suction within the furnace radiator may directly act on the diaphragm 6|. If the draft within the furnace radiator 34 is relatively strong, the diaphragm 5| will be pulled inwardly toward the wall I I of the grain chamber. A pull-,

ing of the diaphragm 6| causes a movement of the rod 56 and thus a clockwise movement of the bell-crank lever 45 as viewed in Figure 2. Such a clockwise movement of the bell-crank lever 45 causes the butterfly valve 38 to pivot about its axis shaft 39 closing the opening in the conduit 31 between the furnace radiator and the suction fan chamber 48. The draft or suctionwithin the furnace radiator is then decreased and'the movement or action on the diaphragm BI is proportionately decreased. 7

A spring 61 is anchored at one end to the wall II at 68 and at its other end is attached to an the conduits 35 and 36 A pressure responsive element such as a.

4 upwardly extending lug 89 at I8. The lug 69 forms part of a clamp member H fixedly attached to the rod member 56. The spring 8'! normally exerts a force in an outward direction on the rod 56 so that the lever arm 58 tends to move toward its outer casing 12. The spring 81 may have its tension adjusted by tightening or loosening of the lock nuts 13. The suction within the furnace radiator 34 must be sufficient to overcome the action of the spring 61, and when as previously described the butterfly valve 38 is partially closed by movement of the diaphragm 6|, the decreased draft within the radiator causes a a releasing of the hold on the diaphragm 81 so that it is partially overcome by a counteraction of the spring 61 which tends to cause movement of the bell-crank lever 45 in a counterclockwise direction resulting in an opening of the butterfly valve 38. The strength of the spring 61 is so adjusted that the valve38 will assume a position. most favorable to complete efficient combustion in the furnace.

Numerous details of construction may be varied over a wide range Without departing from the principles disclosed herein and I therefore do not propose limiting the patent granted hereon otherwise than as necessitated by the appended claims.

What is claimed is:

1. In a suction type grain dryer having a furnace and a suction fan adapted to draw hot air from the furnace upwardly through a column of grain, a furnace flue gas radiator in said column of grain, a conduit joining said radiator with said suction fan, valve means in said conduit for. varying the amount of passage opening between said radiator and said suction fan, and means responsive to the draft in the furnace radiator for controlling said valve means to control the amount of suction applied to the furnace radiator.

2. In a suction type grain dryer having a furnace and a suction fan adapted to draw hot air from the furnace upwardly through a column of grain, a furnace flue gas radiator in said column of grain, a conduit joining said radiator with said suction fan, valve means in said conduit for varying the amount of passage opening between said radiator and said suction fan, and means responsive to the draft in the furnace radiator for controlling said valve means, said means comprising a pressure actuated. device associated with the radiator and directly effecting the position of the valve means by the strength of draft within the radiator.

3. In a suction type grain dryer having a furnace and a suction fan for drawing furnace hot air upwardly through an enclosed column of grain, a furnace flue gas radiator positioned in said column of grain for effecting heat transfer to said grain, a conduit joining said radiator with said suction fan, valve means in said conduit for varying the amount of passage opening between said radiator and said suction fan, means responsive to the draft in the furnace radiator for controlling said valve means, said means comprising a pressure responsive diaphragm communieating with said radiator, and linkage operatively joining said valve means and said diaphragm, whereby movement of the diaphragm will cause movement of said valve means.

1 4. In a suction type grain dryer having a furnace and a suction fan for drawing heat through a mass of grain, a furnace flue gas radiator positioned within said mass of grain, a conduit joining said radiator with said suction fan, valve meansin said conduit for varying the amount of passage opening between "said' radiator and said suction fan, means responsive to the draft in the furnace radiator for controlling said valve means, said means comprising a pressure responsive diaphragm, linkage 'operatively joining said valve 'rnea ns am said diap'hragr'n, spring means adapted to normally 'ac't 'against' said diaphragm tending to open saidwalve means, and a conduit-extendin between said furnace radiator and said diaphragm, whereby an-increased draft within the furnace radiator tends to close said valve means against the action of the spring e n Y *5. In a suction type grain;dryer;having a furnace and a suction fan for carrying heat from the furnace through a mass of grain, a furnace flue gas radiator placed in said mass of grain for more eflicient grain heating, a conduit joining said radiator with said suction fan, valve means in said conduit for varying the amount of passage opening between said radiator and said suction fan, means responsive to the draft in the furnace radiator for controlling said valve means, said means comprising a pressure responsive diaphragm, linkage operatively joining said valve means and said diaphragm, spring means adapted to normally act against said diaphragm tending to open said valve means, a conduit extending between said furnace radiator and said diaphragm, whereby an increased draft within the furnace radiator tends to close said valve means against the action of the spring means, and adjustable limits for said valve means whereby the limits may be adjusted so as not to permit complete opening or closing of the valve means.

6. In a suction type grain dryer having a furnace and a suction fan, a grain drying chamber positioned between said furnace and suction fan, whereby heat is drawn from the furnace by the fan through the grain in the drying chamber, a furnace flue gas radiator having a plurality of heat exchange conduits positioned Within the grain drying chamber, conduit means joining said furnace radiator with said suction fan, valve means within said conduit means for varying the amount of passage therethrough, and automatic means for controlling said valve means responsive to the draft within the furnace radiator.

7. In a suction type grain dryer having a furnace and a suction fan, a grain drying chamber positioned between said furnace and suction fan, whereby heat is drawn from the furnace by the fan through the grain in the drying chamber, a furnace flue gas radiator having a plurality of heat exchange conduits positioned within the grain drying chamber, conduit means joining said furnace radiator with said suction fan, valve means within said conduit means for varying the amount of passage therethrough, automatic means for controlling said valve means responsive to the draft within the furnace radiator, said automatic means including a compartment having a pressure responsive element therewithin, a conduit joining said furnace radiator with the compartment on one side of the pressure responsive element, and linkage means joining said valve means with said pressure responsive element, whereby the valve means is controlled by movements of the pressure responsive element.

8. In a suction type grain dryer having a furnace and a suction fan, a grain drying chamber positioned between said furnace and suction fan, whereby heat is drawn from the furnace by the fan through the grain in the drying chamber, a furnace flue gas radiator having a plurality of neat exchange conduits positioned within the g ram'arying chaiiiber, ccnduitimeans joi riing said inmate radiator W" h s'aid slletion fan, valve means ivvithin said c *duit means for varyin the amount of passage therethrough, automatic means for controlling "said valve inea'r i's responsive to "ti f draft the r-ur nate r-ad-iaton-said autom'a means including a compartment having a d'iaphragrn therewithin, a conduit oining 'said furnace radiator with' the compartment 'on one side of the diaphragm, and linkage means joining said'valve :means with said diaphragm, whereby the valve means is 'controlled 'bymovemen't's bfthe' diaplfi agm.

9. In a suction type grain dryer having a furnace and a suction fan, a-gra'in drying chamber positioned between-said furnace and suction fan, whereby heat is drawn from the furnace by the fan through the grain in the drying chamber, a furnace flue gas radiator having a plurality of heat exchange conduits positioned within the grain drying chamber, conduit means j Oining said furnace radiator with said suction fan, valve means within said conduit means for varying the amount of passage therethrough, automatic means for controlling said valve means responsive to the draft within the furnace radiator, said automatic means including a compartment having a diaphragm therewithin, a conduit joining said furnace radiator with the compartment on one side of the diaphragm, linkage means joining said valve means with said diaphragm, and adjustable spring means associated with said diaphragm for normally tending to open said valve means, whereby the valve means is closed proportionately to the amount of draft within the furnace radiator sufficient to overcome the action of the spring means.

10. In a suction type grain dryer having a furnace and a suction fan, a grain drying chamber positioned between said furnace and suction fan, whereby heat is drawn from the furnace by the fan through the grain in the drying chamber, a furnace flue gas radiator having a plurality of heat exchange conduits positioned within the grain drying chamber, conduit means joining said furnace radiator with said suction fan, valve means within said conduit means for varying the amount of passage therethrough, automatic means for controlling said valve means responsive to the draft within the furnace radiator, said automatic means including a compartment having a diaphragm therewithin, a conduit joining said furnace radiator with the compartment on one side of the diaphragm, linkage means joining said valve means with said diaphragm, adjustable spring means associated with said diaphragm for normally tending to open said valve means, whereby the valve means is closed proportionately to the amount of draft within the furnace radiator, and adjustable limit means associated with said linkage for limiting valve movement.

11. In a suction type grain dryer having a furnace and a suction fan, a grain drying chamber positioned between said furnace and suction fan, whereby heat is drawn from the furnace by the fan through the grain in the drying chamber, a furnace flue gas radiator having a plurality of heat exchange conduits positioned within the grain drying chamber, conduit means joining said furnace radiator with said suction fan, butterfly valve means Within said conduit means for varying the amount of passage therethrough, automatic means for controlling said valve means re- 7 sponsive to the draft within the furnace radiator, said automatic means including a compartment outside said grain chamber having a diaphragm therewithin, a conduit joining said furnace radiator with the compartment on one side of the diaphragm, linkage means joining said valve means with said diaphragm, adjustable spring means associated with said diaphragm for normally tending to open said valve means, whereby the valve means is closed proportionately to the amount of draft within the furnace radiator, and adjustable limit means associated with said linkage tor limiting valve movement.

ALBERT B. WELTY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES The Link Belt-Roto Louvre Dryer, Book No. 1911, The Link-Belt Company, copyright 1941,

15 pages 16, 17, 18 and 19. 

